The “Cabinet” is said to define the flow domain of interest in Icepak but it may not be the case with every geometry that the fluid domain is simply a cuboid which can be realized just merely by resizing the cabinet.

I had some exposure to ICEM CFD where the flow domain is defined by a material point (or the block that captures the CAD geometry) what is the kind of analogy Icepak likely applies to model the flow domain

For instance consider a CAD geometry as a cuboid on top of which there is a cylindrical passage for air to enter. In this case how do we model the flow domain in Icepak